Method of making soft magnetic amorphous metal electromechanical component

ABSTRACT

A three dimensional soft magnetic metal mass suitable for milling is formed wrapping soft magnetic metal ribbon into a three dimensional shape and then applying adhesive to the three dimensional shape. The adhesive permeates the three dimensional shape. The adhesive is then cured. If the soft magnetic metal mass is made as a toroid, then it could be processed into an electromechanical component. The electro-mechanical component would then be suitable for use in very high frequency electric motors.

This application is a continuation-in part of U.S. application Ser. No.10/763,728, filed Jan. 23, 2004, which is a continuation-in-part of U.S.application Ser. No. 10/458,944, filed Jun. 11, 2003 (now U.S. Pat. No.7,018,498).

BACKGROUND OF THE INVENTION

Multi-pole rotating electro-mechanical devices, such as motors,generators, re-gen motors, alternators, brakes and magnetic bearings arecomprised of rotors and electro-mechanical components. AC motors rotateby producing a rotating magnetic field pattern in the electro-mechanicalcomponent that causes the rotor to follow the rotation of this fieldpattern. As the frequency varies, the speed of the rotor varies. Toincrease the speed of the motor, the frequency of the input source mustbe increased.

High frequency motors manufactured with the proper materials can be veryefficient. For certain applications, like electric or hybrid cars,highly efficient electric motors are desirable.

The construction of electro-mechanical components for high frequencyelectric motors and generators is problematic. Iron or steel componentsare quite common in electric motors and generators. However, at highfrequencies, such as those greater than 400 Hz, conventional iron orsteel components are no longer practical. The high frequency of the ACsource increases the core losses of the iron or steel components,reducing the overall efficiency of the motor. Additionally, at very highfrequencies, the component may become extremely hot, cannot be cooled byany reasonably acceptable means and may cause motor failure.

For construction of electro-mechanical components used in high frequencyelectric motors, ribbon made from soft magnetic material providesdistinct advantages. defined as 0.008″ and thicker, non grain orientedwith a typical Si content of 3%+/−12% or 2) alternate soft materialsthat are 0.007″ or thinner with Si content of 3% to 7%, amorphous, ornanocrystalline alloys and other grain oriented or non grain orientedalloys. Some soft magnetic ribbon materials exhibit inherentcharacteristics that make their use in high frequency electro-mechanicalrotating devices highly desirable. Some soft magnetic ribbons are easyto magnetize and demagnetize, which means an electromechanical componentmade with these metals would have low power loss, low temperature riseat high frequency, extremely fast magnetization and easy conversion ofelectrical to mechanical energy. An electro-mechanical component made ofsuch an metal would generate less core losses and be able to operate atmuch higher frequencies, resulting in motors and generators ofexceptional efficiency and power density.

Soft magnetic materials are commercially produced as ribbon or strip. Apreferred example of a soft magnetic metal ribbon is Metglas®, which isan amorphous material, manufactured by Honeywell, Inc. Soft magneticmetal ribbons are very thin and of varying width. Manufacturingcomponents of soft magnetic metal ribbon requires winding the softmagnetic ribbon into a shape and then heat processing the shape. Simplethree dimensional shapes, such as toroids, can currently be constructedfrom soft magnetic metal ribbon.

However electromechanical components are often not simple threedimensional shapes. The electromechanical component can have numerousslots for accommodating motor coils in a generally toroidal structure.

Attempts to create complex three dimensional configurations from softmagnetic metal ribbon have heretofore been commercially unsuccessful.Various manufacturing techniques have been attempted by industry such asbut not limited to: wire electrical discharge machining, electrochemicalcreep grinding, conventional electrical discharge machining, cutting,stamping, acid etching and fine blanking. None have proven satisfactoryfor reasons such as cost-effectiveness, manufacturing repeatability, orprocess cycle time.

This inability to fabricate complex three dimensional shapes from softmagnetic ribbon has been the significant impediment to producing highefficiency axial flux motors and generators. A method to produceelectromechanical components from soft magnetic ribbon in a costeffective, end use functional, high volume capable method that will alsoprovide substantial design flexibility for end use requirements ishighly desirable.

SUMMARY OF THE INVENTION

A method for forming a three dimensional soft magnetic metal masssuitable for milling consists of wrapping soft magnetic metal ribboninto a three dimensional shape, then applying adhesive to the threedimensional shape. The adhesive is then cured and the cured form ismechanically constrained in three dimensions. The method results in ansoft magnetic metal mass which can withstand the mechanical stresses ofmachining. The three dimensional soft magnetic metal form can be milledusing a horizontal mill, a vertical mill, a computer numeric control(CNC) machine, or any other common milling equipment. Thus, complexthree dimensional soft magnetic metal shapes can be created.

The ability to create three dimensional soft magnetic metal shapesallows the use of soft magnetic metal for a variety of applicationsheretofore foreclosed by the mechanical characteristics of soft magneticmetal ribbon.

To manufacture an soft magnetic electromechanical component, softmagnetic metal ribbon is wound into a toroid. The toroid is then placedin a milling assembly. Adhesive is applied to the toroid, and thencured. The toroid is then milled into an electromechanical componentshape, and then thermally processed into a electromechanical component.

These and other objects, advantages and features of the invention willbe more readily understood and appreciated by reference to the detaileddescription of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a soft magnetic metal ribbon being wound on an inner ring.

FIG. 2 shows an inner containment hat.

FIG. 3 shows an outer containment hat.

FIG. 4 shows a milling assembly.

FIG. 5 shows a milling assembly being milled.

FIG. 6 shows a soft magnetic metal electromechanical component.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows soft magnetic metal ribbon 10 being wound about a windingaxis 11 on an inner ring 14. Winding machine 13 contains soft magneticmetal ribbon roll 12. Inner ring 14 is placed on winding plate 16. Softmagnetic metal ribbon 10 is wound on inner ring 14, forming softmagnetic metal toroid 18. Soft magnetic metal toroid 18 has an innerside surface 15, an outer side surface 17, a top 19, and a bottom 21.

While FIG. 1 shows the formation of an soft magnetic metal toroid 18, itwill be appreciated that a three dimensional shape could be created witha geometry distinctly different from the soft magnetic metal toroid 18.For example, it would be possible by winding around four corners tocreate a rectangular prism.

Soft magnetic metal ribbon 10 can be wound using a variety of machinesand methods. Preferably, a consistent, firm toroid will have at least an85% wind density compared to the inherent ribbon density. Soft magneticmetal toroid 18 is then removed from winding plate 16. Soft magneticmetal ribbon 10 can be wound around the inner ring 14 while attached tothe inner containment hat 20 as a single unit.

An adhesive is then applied to the soft magnetic ribbon toroid 18 in amanner to permeate the soft magnetic metal toroid 18. Inner ring 14 isstill contained within the soft magnetic ribbon toroid 18. A suitableadhesive is Scotch Cast adhesive by 3M, diluted by acetone so as toachieve about a 20% mix by volume. The adhesive is applied to softmagnetic ribbon toroid 18 by an ambient atmospheric soak process. Softmagnetic ribbon toroid 18 is immersed in the adhesive until the adhesiveinfiltrates the layers.

Alternatively, the adhesive could be applied by immersing soft magneticribbon toroid 18 into the adhesive inside a vessel that is evacuated ofair. The vacuum created would enhance the infiltration of the adhesiveinto the soft magnetic ribbon toroid 18 layers. Adhesive could also beapplied to the soft magnetic ribbon during the winding process utilizinga wet spray or dry electrolytic deposition process. Alternative resins,epoxies or adhesives may be used. Different brands as well as differenttypes of resins, epoxies or adhesives may be used. Heat cured epoxiesthat require various temperatures as well a two stage epoxies that cureat room temperature would also be suitable.

After soft magnetic ribbon toroid 18 is sufficiently infiltrated withadhesive, soft magnetic ribbon toroid 18 is allowed to drain. Once dry,soft magnetic ribbon toroid 18 is placed inside an oven for curing.Importantly, the temperature for heat treating the adhesive be afraction of the temperature for heat processing soft magnetic metalribbon 10. A preferable fraction is ½, although fractions of ¼ and ¾might also be satisfactory.

FIG. 2 shows inner containment hat 20. Inner containment hat 20 is acylinder comprised of a number of columns 22 extending upward from theinner containment hat base 24. Fingers 26 extend outward from columns 22at approximately a right angle. Fingers 26 increase in width as theyextend further from the columns 22. Fingers 26 are arranged in a circle,forming an annulus 28. The columns 22 and fingers 26 form a plurality ofinner containment hat grooves 29. Columns 22 of inner containment hat 20are placed inside inner ring 14.

The height of columns 22 is approximately equal to the height of thesoft magnetic metal toroid 18. The diameter of the soft magnetic metaltoroid 18 is about equal to the diameter of the annulus 28.

Following the placement of inner containment hat within soft magneticmetal toroid 18, outer containment hat 30 shown in FIG. 3, is placedaround soft magnetic metal toroid 18.

Outer containment hat 30 is cylindrical, with a base 32. Bars 34 extendupward from base 32. At the top of each bar 34 is a lug 36 extendinginward. Lug 36 for each bar 34 forms a flange for securing the amorphousmetal toroid 18 within outer containment hat 30. Bars 34 and lugs 36form a plurality of outer containment hat grooves 38.

Milling assembly 40, shown in FIG. 4, is then formed. Soft magneticmetal toroid 18, still containing inner ring 14, along with the innercontainment hat 20 is placed within outer containment hat 30. Lugs 36and fingers 26 are aligned. Milling assembly 40 contains the softmagnetic metal toroid 18 within a toroidal geometry. Alternatively, softmagnetic metal toroid 18 could be placed within outer containment hat 30and inner containment hat 20 prior to treatment with the adhesive.

After application of the adhesive and placement within the mechanicalconstraints of the inner ring 14, inner containment hat 20, and outercontainment hat 30, the soft magnetic metal toroid 18 has sufficientstructural integrity to withstand the stresses of milling.

Milling plate 44 is placed on the bottom of the soft magnetic metaltoroid 18. Milling plate 44 could be the same as winding plate 16.

Soft magnetic metal toroid 18, having been treated with an adhesive, isthus firmly contained within a structure, allowing soft magnetic metaltoroid 18 to be milled and formed in three dimensions. Complex shapescan thus be constructed from the metal ribbon toroid 18, allowingstructures such as electromechanical components to be made from the softmagnetic metal toroid 18.

As illustrated by FIG. 5, milling assembly 40 is placed in mill 50. Mill50 could be a horizontal mill, a vertical mill, a CNC machine, or anyother type of mill. However, mill 50 should preferably have the axis ofrotation of the mill tools 52 perpendicular to the axis of the softmagnetic metal toroid 18. By having the axis of rotation of the milltool 52 perpendicular to the axis of the soft magnetic metal toroid 18,the depth and width of the slots milled into the soft magnetic metaltoroid 18 can be finely controlled.

Mill 50 cuts slots or other geometries into the soft magnetic metaltoroid 18. Inner ring 14, still contained within soft magnetic metaltoroid 18, acts as a positive mechanical stop for the inside edge ofsoft magnetic metal toroid 18. Inner ring 14, in conjunction with theepoxy, does not allow strips of soft magnetic metal ribbon 10 toseparate during machining, thereby producing clean and accurate cuts.

After the soft magnetic metal toroid 18 is milled into anelectromechanical component shape, milling assembly 40 is removed frommill 50. Milling assembly 50 is then thermally processed in accordancewith the recommendations of the manufacturer of soft magnetic metalribbon 10 as required. If the amorphous metal ribbon 10 is Metglas®,thermal processing consists of placing milling assembly 50 into a vacuumfurnace at 695 degrees Fahrenheit for approximately sixty minutes. Somesoft magnetic ribbon materials require thermal processing to achieve thedesired magnetic properties while others require thermal processing toproperly relieve the stresses in the milled electromechanical componentshape as a result of the milling process. It is conceivable that, givenproper mechanical containment during milling, some materials that do notrequire thermal processing for magnetic properties could forego thethermal processing.

Following thermal processing, the milling assembly 40 is disassembled byremoving retainer 42, outer containment 30, inner containment hat 20,and inner ring 14. Soft magnetic metal toroid 18 has thus been made intoan soft magnetic metal electromechanical component 60, shown in FIG. 6.

The method as described allows for the creation of three dimensionalforms from soft magnetic metal ribbon. The applications for such threedimensional forms could be as electromechanical components for a varietyof machines.

The above description is of the preferred embodiment. Variousalterations and changes can be made without departing from the spiritand broader aspects of the invention as defined in the appended claims,which are to be interpreted in accordance with the principles of patentlaw including the doctrine of equivalents. Any references to claimelements in the singular, for example, using the articles “a,” “an”,“the,” or “said,” is not to be construed as limiting the element to thesingular.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A method for forming athree dimensional soft magnetic metal mass suitable for milling,comprising the steps of: winding a commercially produced soft magneticmetal ribbon on an inner ring placed on a winding plate into a toroidhaving three dimensional shape; removing said wound toroid from saidwinding plate and applying a liquid adhesive allowing permeation of saidliquid adhesive; curing said wound toroid with said liquid adhesive atan adhesive curing temperature; placing said adhesive bonded woundtoroid in a milling assembly comprising an inner containment bottom hatand an outer containment hat, said outer containment hat having aplurality of slots for the passage of a milling cutter; milling slots insaid adhesive bonded toroid; removing the milled adhesive bonded toroidfrom said milling assembly; and thermally processing said millingassembly with said adhesive bonded milled toroid at a temperaturerelieving milling stresses and enhancing magnetic properties.
 2. Amethod for manufacturing a soft magnetic metal electro-mechanicalcomponent comprising the steps of: winding commercially produced softmagnetic metal ribbon on an inner ring placed on a winding plate into atoroid; removing said wound toroid from said winding plate and applyinga liquid adhesive allowing permeation of said liquid adhesive; curingsaid wound toroid with said liquid adhesive at an adhesive curingtemperature; placing said adhesive toroid in a milling assemblycomprising an inner containment bottom hat and an outer containment hat,said outer containment hat having a plurality of slots for the passageof a milling cutter; milling slots in said adhesive bonded toroid into aelectro-mechanical component shape and removing said adhesive bondedtoroid from the milling assembly; applying a magnetic field to saidadhesive bonded toroid; and thermally processing the electro-mechanicalcomponent shape into a electro-mechanical component at a thermalprocessing temperature improving the magnetic properties of the toroid.3. The method of claim 2 where the step of containing said adhesivebonded toroid within a toroidal geometry comprises the steps of:applying a liquid adhesive to allow permeation of the adhesive into thewound toroid; and curing the adhesive at a adhesive curing temperaturesaid adhesive curing temperature being below said thermal processingtemperature required for improving the magnetic properties of the woundcured toroid, whereby the exposure to said adhesive curing temperaturedoes not degrade mechanical properties of said adhesive bonded toroid.4. The method of claim 3 where the step of applying the liquid adhesiveto the wound toroid comprises an atmospheric soak process.
 5. The methodof claim 3 where the step of applying liquid adhesive to the toroidincludes the steps of: providing a vessel containing the liquidadhesive; immersing the wound toroid in the liquid adhesive; andevacuating the vessel.
 6. The method of claim 3 where the step of curingthe liquid adhesive at said adhesive curing temperature and the step ofthermally processing the electro-mechanical component shape occurs atthe thermal processing temperature, and where the adhesive curingtemperature is a fraction of the thermal processing temperature wherebythe exposure to said adhesive curing temperature does not degrademechanical properties of the electro-mechanical component shape.
 7. Themethod of claim 6 where the fraction is about ½.
 8. The method of claim6 where the fraction is about ¾.
 9. The method of claim 6 where thefraction is about ¼.
 10. The method of claim 2 where the wound toroidhas a ribbon winding axis, and the step of milling the wound toroid intothe electro-mechanical component shape comprises milling the woundtoroid with the cutting tool rotating in an axis perpendicular to thewinding axis.
 11. The method of claim 2 where the wound toroid has aribbon winding axis, and the step of milling the wound toroid into theelectro-mechanical component shape consists of milling the wound toroidwith the cutting tool rotating exclusively in an axis perpendicular tothe ribbon winding axis.
 12. The method of claim 2 where said adhesivebonded toroid has an inner side surface, an outer side surface, a topand a bottom.
 13. A method for manufacturing a soft magnetic metalelectro-mechanical component comprising the steps of: windingcommercially produced soft magnetic metal ribbon on an inner ring and ainner containment bottom hat placed on a winding plate into a toroid;removing said wound toroid on the inner ring and the inner containmentbottom hat from said winding plate and applying a liquid adhesive,allowing permeation of said liquid adhesive; curing said wound toroidwith said liquid adhesive at an adhesive curing temperature; placingsaid adhesive wound toroid in a milling assembly comprising an outercontainment hat, said outer containment hat having a plurality of slotsfor passage of a milling cutter; milling slots in the wound adhesivebonded toroid into a electro-mechanical component shape; applying amagnetic field to said adhesive wound bonded toroid; and thermallyprocessing the electro-mechanical component shape into aelectro-mechanical component at a thermal processing temperatureimproving the magnetic properties of said adhesive wound bonded toroid.